Design and Validation of a Multi-User Architecture and Multiplexing Techniques for Lunar Proximity Communication Links

This thesis proposes the design of a multi-user architecture for Lunar proximity communication links, with a focus on Data Link Layer and Physical Layer multiplexing techniques. The core of the work is the design and validation of the strategies adopted at the Physical Layer. The study is part of ANDROMEDA, a Lunar communication service based on a constellation of microsatellites designed by the Italian aerospace company Argotec. After a brief description of ANDROMEDA’s baseline architecture and concept of operations, the definition of system requirements to support multi-user communications follows. The protocol stack is then defined with a description of involved Consultative Committee for Space Data System (CCSDS) Standards and a couple of use cases are also presented. The main guidelines for the development of the work have been the Space Frequency Coordination Group (SFCG) frequency allocation recommendation for the Lunar region, the Future Lunar Communication Architecture document released by the Interagency Operations Advisory Group (IOAG), and especially the Draft LunaNet Interoperability Specification written by NASA Goddard Space Flight Center in cooperation with ESA. All of them give essential information for the protocol stack trade-off analysis and the subsequent Data Link Layer study. Based on it, the multiplexing processes of the Data Link Layer are defined. Following a brief discussion about working frequencies and modulations, the multiplexing stage at the Physical Layer is realized by means of a synthesizer and its description and working parameters are provided. The document ends with the description of the tests conducted to validate the system following the realization of a dedicated software in C++. Tests were carried out exploiting a Software Defined Radio (SDR) and a spectrum analyzer was used to collect results. The latter have demonstrated the architecture feasibility.